From 70513418a523d58d04b776945789c08bf3a688a9 Mon Sep 17 00:00:00 2001
From: Nayana Bidari <nybidari@google.com>
Date: Mon, 10 Feb 2025 09:37:25 -0800
Subject: [PATCH] Fix data race in packetmmap endpoint.

PiperOrigin-RevId: 725246804
---
 pkg/sentry/socket/netstack/packetmmap/endpoint.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pkg/sentry/socket/netstack/packetmmap/endpoint.go b/pkg/sentry/socket/netstack/packetmmap/endpoint.go
index 04f5804fea..600f0d3c0c 100644
--- a/pkg/sentry/socket/netstack/packetmmap/endpoint.go
+++ b/pkg/sentry/socket/netstack/packetmmap/endpoint.go
@@ -68,8 +68,9 @@ type Endpoint struct {
 
 	// +checklocks:mu
 	mode ringBufferMode
+	// +checklocks:mu
+	cooked bool
 
-	cooked    bool
 	packetEP  stack.MappablePacketEndpoint
 	reserve   uint32
 	nicID     tcpip.NICID
@@ -196,6 +197,7 @@ func (m *Endpoint) HandlePacket(nicID tcpip.NICID, netProto tcpip.NetworkProtoco
 		m.stack.Stats().DroppedPackets.Increment()
 		return
 	}
+	isCooked := m.cooked
 	m.mu.Unlock()
 
 	if pkt.GSOOptions.Type != stack.GSONone && pkt.GSOOptions.NeedsCsum {
@@ -206,7 +208,7 @@ func (m *Endpoint) HandlePacket(nicID tcpip.NICID, netProto tcpip.NetworkProtoco
 	}
 
 	pktBuf := pkt.ToBuffer()
-	if m.cooked {
+	if isCooked {
 		pktBuf.TrimFront(int64(len(pkt.LinkHeader().Slice()) + len(pkt.VirtioNetHeader().Slice())))
 		// Cooked packet endpoints don't include the link-headers in received
 		// packets.